The present invention relates to devices used to communicate data over telephone lines, and more particularly, to handset orientation tolerant bi-directional acoustic modems.
Patients with specific health conditions may require constant or frequent observation by their physicians. However, confinement to a health care facility during this observation is typically not desirable for the patient. As a solution to this problem, physicians are increasingly monitoring their patients with remote devices. The physician is still able to observe and examine the biomedical data of the patient, and the patient enjoys a certain degree of freedom.
When the patient is remotely monitored, they typically have some type of event recorder that acquires the biomedical data of interest. At certain intervals established by the physician, the patient needs to transmit the data to a central site for analysis by a health care provider. Generally, the data is transmitted over a telephone line using a conventional acoustic modem.
Conventional acoustic modems typically rely on one way communication from the event recorder to a central site where the data can be reviewed by the health care provider. For operation, the patient must dial the phone, communicate over the phone with a receiving authority at the central site to determine when transmission can begin, align the microphone of the telephone handset with the speaker of the acoustic modem, trigger the transmission, determine when the transmission is complete, and determine whether transmission of the data needs to be repeated. Many of the patients that are remotely monitored are elderly, sick, feeble, intimidated or confused by the monitoring procedures and equipment, or not highly motivated to operate the transmission of the biomedical data to the central site. Additionally, the patients may be agitated because they have just experienced some type of medical symptom. Thus, it would be advantageous to provide a device that simplifies the process of transmission of biomedical data to the central site for the patient.
When the patient transmits the data using a conventional acoustic modem, it is important to align the speaker or transmitter box of the event recorder with the microphone on the handset of the telephone. The transmitter box of the event recorder includes an acoustic coupler or modem on its top surface. The handset of the phone through which the data is being transmitted to a receiving station at the central site (e.g., hospital or physician""s office) is placed within acoustic range of, or adjacent to, the transmitter box. A misconfiguration of the handset and transmitter box may corrupt the communication of data and render the data received at the central site useless. When a sampling of data takes several minutes to acquire and transmit, this can be a frustrating experience for both the patient and the receiving authority. In such a case, the patient must make and transmit the reading over again. Thus, it would be advantageous to provide a device that minimizes errors and saves time by simplifying the process of aligning the telephone handset with the transmitter box, and by automatically causing the data that is being transmitted to be retransmitted if the transmission was corrupted.
Accordingly, the invention provides a handset orientation tolerant bi-directional acoustic modem. The acoustic modem includes two transducers (a first transducer and a second transducer) and a programmable controller. Each transducer is capable of functioning as both a transmitting unit to emit acoustic signals, and as a receiving unit to receive communication from the central site. After a telephone handset is aligned with the acoustic modem, the controller determines the orientation of the telephone with respect to the two transducers of the acoustic modem. Based on the determination of the orientation, the controller selectively assigns functionality to each of the two transducers. One of the two transducers acts as the receiving unit and the other of the two transducers acts as the transmitting unit. The acoustic modem is coupled to a data source such as an event recorder, and to a converter. The data source acquires biomedical data and the converter receives, amplifies, conditions, and encodes the biomedical data for emission as an acoustic signal by the transmitting unit of the acoustic modem. The acoustic modem may also be coupled to a memory unit that is utilized to store data before transmission to the central site.
For operation, the patient only needs to align the microphone and the speaker of the telephone handset with the two transducers of the acoustic modem. The microphone and the speaker can be aligned with the two transducers in either orientation (i.e., the speaker on the first transducer and the microphone on the second transducer, or the microphone on the first transducer and the speaker on the second transducer). The controller determines which of the two transducers is aligned with the speaker of the handset by sampling both transducers for a detectable dial tone or other tone of the telephone. When a dial tone is properly detected in one of the two transducers, that transducer is assigned the functionality of the receiving unit to receive communication from the central site. The other of the two transducers is then assigned the functionality of the transmitting unit to emit the acoustic signals. After the functionality of each transducer is assigned, the central site is automatically dialed by emitting dialing tones with the transmitting unit. The receiving unit waits for a response from the receiving station of the central site. Once the response is received, the transmission protocol may proceed. After the transmission protocol is completed, the patient completes the process by hanging up the phone.
The transmission protocol of the invention includes a bi-directional transmission of data. The communication of data between the remote location and the central site can be either half duplex or full duplex. In one embodiment, the data is transmitted from the remote location to the central site in small packets of data with sequence numbers. The receiving station acknowledges whether or not the transmission of a small packet of data was proper. This acknowledgement is received by the receiving unit of the acoustic modem. If a negative acknowledgement, or no acknowledgement, is received by the receiving unit, the small packet of data is retransmitted to ensure complete transmission of uncorrupted data. The receiving station is able to organize the small packets of data in proper sequence by sequentially organizing the sequence numbers that are attached to the small packets of data.
These features as well as other advantages of the invention will become apparent upon consideration of the following detailed description and accompanying drawings of the embodiments of the invention described below.